Officials from the agency are continuing their probe of the propylene fire and explosions that heavily damaged an olefins unit at the Formosa Plastics facility, injuring approximately 13 workers. Most injuries were minor, but two workers were admitted to the burn unit at a Galveston hospital, and one remains hospitalized there, according to CSB.
As for the suspected cause of the blast, "witness accounts indicate that a forklift truck towing an air supply trailer may have collided with a drain line near a ground-level control valve station carrying highly flammable liquid propylene," CSB lead investigator Jim Lay, P.E., said.
"We intend to gather additional evidence before confirming this theory," Lay said. "Shortly after the trailer entered the vicinity of the valve station, witnesses saw a downward jet of escaping hydrocarbon, which formed a rapidly expanding vapor cloud. Within a few minutes, the vapor cloud found an ignition source, causing an explosion and fire."
Major fires continued for a number of hours as additional piping was damaged and more flammable hydrocarbons were released.
Lay noted Oct. 14 that access to the exact point of origin of the release was still restricted due to structural hazards, residual flammable materials, and ongoing emergency response and firefighting activities.
"Portions of the olefins unit where the incident was centered show extensive damage from heat," Lay said. "The site shows relatively little blast damage, consistent with a series of unconfined, open-air explosions or deflagrations."
Immediate issues before the investigative team include characterizing the extent of secondary damage from the explosion and examining the effectiveness of the facility's vehicular control policies and the protection of vulnerable piping from vehicular collision.
Lay said team members would be returning to the plant as early as this week to continue the probe.
Community Impact Studied
In addition to work at the Formosa site, investigators went into the Point Comfort and Port Lavaca communities to assess the impact of the incident.
One school near the plant was temporarily evacuated on the day of the incident and two highways were closed for several hours. Investigators determined that approximately 15 members of the public sought medical evaluations at area hospitals; none was admitted to the hospital for treatment.